Method of making a high-density explosive



Patented Sept. 20, 1949 METHOD OF MAKING A HIGH-DENSITY EXPLOSIVE Ludwig F. Audrieth and De Witt D. Sager, Dover, N. J.', assignors to the United States of America as represented by the- Secretary of War No Drawing. Application March 20, 1944,

Serial No. 527,323

(01.52-22) (Granted underthe act of March 3, 1883, as

1 Claim.

The invention described herein may be manufactured'and' used by' or for the Governmentfo'r governmental purposes without the payment to us of any'royalty thereon.

The'present' invention .relates to new high explosive compositions consisting of trinitrotoluene, trinitrophenyl methylnitramine, and cyclotrinlethylenetrinitramine.

Specifically this invention relates to compositions of matter possessing high brisance and high explosive power based upon the'use of mixtures consisting of trinitrophenyl methyl nitramine and trinitrotoluene or mixtures of cyclotrimethylenetrinitra'mine and trinitrotoluene, either singly or in combination to produce a ternary composition in allqcases consisting of trinitrotoluene, trinitrophenyl methyl nitramine and cyclotriinethylenetrinitramine. The resulting three component,explosives'thus broadly specified are .charact erizedby their superior properties as high'explosive charges for use in loading and filling, preferably by cast loading, of shells, bombsinines, bursters, grenades, various demolition chargesand other ammunition.

In order: to make the basisof our discoveries clear," it would be wen to review briefly the status of various useful high explosives which are now commonly employed in particular for military purposes? Binary mixtures consisting of trinitrotoluene plus trinitrophenyl methyl nitramine or cyclotrimethylenetrinitramine, respectively, are widely used as military explosives, not only because they possess satisfactory thermal stability and high brisance but also because they can be loaded into shells, bombs, mines, etc., by a process known "as cast or melt loading. Such binary mixtures'are commonly prepared by adding to molten trinitrotoluene either trinitrophenyl methyl nitramine or cyclotrimethylenetrinitramine, both'o'i which'are more powerful ex plosives thanthe trinitrotoluene which serves as the carrier. In the case of the 'mixturecomprising trinitrotoluene and trinitrophenyl methyl nitran'lin, appreciable solubility of trinitrophenyl methyl nitramine in the liquid trinitrotoluene is involved. Thus,'for instance, a liquid melt can be 'prepared very easily at temperatures between 90am 100C. containing 40 parts by weight of trinitrophenyl methyl 'nitramine and-60parts by weight of trinitrotoluene. Melts containing higher percentages of trinitrophenyl methyl nitramine 'may also be'prepa'red but are more viscous in view of the fact that the limit of solubilitybf trinitrophenyl methyl nitramine in trinitrotoluene is exceeded." 'In the case-ofthe amended April 30, 1928; 370 0. G. 757) 2 V binary mixture comprising trinitrotoluene and cyclotrimethylenetrinitramine the solubility of cyclotrimethylenetrinitramine in trinitrotoluene at temperatures ordinarily employed in melt loading operations is ratherlimited. Cyclotrimethylenetrinitramine under these conditions is soluble to the extent of only 6% in molten trinitrotoluene. It is possible, however, to prepare mixtures of cyclotrimethylenetrinitramine andtrinitrotoluene which can be cast in the form of a slurry or suspension and which possess sufficiently high fluidity to make pouring of such melts possible. Thus, one particular mixture consisting of cyclotrimethylenetrinitramine and 40% trinitrotoluene is readily pourable at temperatures between and C. so that the cast loading processes can be carried out without difliculty. It should be pointed out here that the temperatures 90105 C. are specified, the upper limit being the highest permissible consistent with safe operation and handling of such materials. 7

Such binary mixtures being capable of cast loading may, therefore, be employed to give relatively high density exposive charges of higher brisance and power than are obtainable with cast trinitrotoluene by itself. In all these cases, the resulting binary mixtures, while more sensitive to shock and impact than trinitrotoluene, are nevertheless considerably less sensitive than the added component by itself, thus reducing the hazards which attend the loading operations. It is, of course, possible to press load such materials as pure cyclotrimethylenetrinitramine and pure trinitrophenyl methyl nitramine but high pressures are necessary, to achieve high density charges with the result that operations of this sort are carried out only in special and limited cases and would not be suitable for large caliber shells, bombs or mines.

The present invention is based upon the discovery that it is possible to make use of binary mixtures such as trinitrotoluene plus trinitrophenyl methyl nitramine, and trinitrotoluene plus cyclo trimethylenetrinitramine for the production of ternary mixtures of high explosives which not only possess satisfactory thermal stability but are characterized by higher power and greater brisance than the binary mixtures by themselves. Thus, it is possible to make use of a mixture comprising trinitrotoluene plus trinitrophenyl methyl nitramine and add to it appreciable quantities of cyclotrimethylenetrinitramine to give a ternary mixture consisting of trinitrophenyl methyl nitramine, trinitrotoluene and cyclotrimeth'ylene toluene and add to such binary carrier, appreciable quantities of trinitrophenyl methyl nitramine, such addition resulting in the production of a high explosive composition of higher explosive power than the binary mixture ,which served as the carrier. It is possible in both of these instances broadly outlined hereinabove to obtain high density explosive charges which possess greater power, brisance and have more pronounced fragmentation effects than any 4 ten percent greater than that of the binary mixture which served as the liquid carrier.

Example II It is not necessary, of course, to be limited to -a.40-60 mixture but as was emphasized in the earlier discussion, preformed mixtures containing trinitrophenyl methyl nitramine in excess of this specified amount do not consist of a completelyliquid phaseat temperatures between 90 '1 and 100 C. but contain some of the trinitrophenyl methyl nitramine in suspension. In effect, this means that there is less of the liquid binary carrier available to serve as a suspending binary compositions heretofore known'in the patent literature or recorded in the pertinent art. While it is possible to prepare the desired high explosive consisting of trinitrotoluene, trinitrophenyl methyl nitramine and cyclotrimethylenetrinitramine over a wide range of combination of the three ingredients, we prefer to use those which at temperatures commonly employed in melt loading operations possess suificient fluidity so thatthey may be poured readily and thereby loaded by conventional loading procedures; Ternary mixtures which are not readily pourable may, however, be extruded, stemmed or lobloaded over this same temperature range. Cer tain other combinations which can neither be cast nor hot loaded, as specified can be press loaded in particular cases and for particular purposes.

Another advantage possessed by the trinitrotoluene, trinitrophenyl methyl nitramine, cyclotrimethylenetrinitramine, ternary composition is the fact that the ternary eutectic temperature is relatively high. This is not the case with a great many other compositions, which cannot be used because of the fact that low melting eutectic mixtures are formed. The trinitrotoluena'tri- 'nitrophenyl methyl nitramine, cyclotrimethylenetrinitramine, ternary system has an eutectic melting point at 66.8 C. It will, therefore, not tend to undergo exudation from loaded components under the ordinary conditions of storage and use.

The new explosive compositions described broadly in the above discussion can best be visualized in the exemplifications of typical ternary mixtures. In presenting such examples, it is to be understood, however, that these are not to be considered as limiting cases but are merely presented in order to make clear the significance of our discoveries as new and valuable contributions to the number of military explosives now employed.

Example I As typical of the ternary compositions wherein a preformed mixture of trinitrotoluene and .trinitrophenyl methyl nitramine is used as the carrier, there has been prepared the desired high explosive composition by adding 60 parts by weight of .cyclotrimethylenetrinitramine to 40 parts of a liquid melt of a mixture containing 40% trinitrophenyl methyl nitramine and 60% trinitrotoluene. At temperatures between 90 and 100 C. this high explosive possesses satisfactory fluidity so that it can be poured and cast readily even though it is in the form of a suspension. On cooling, this explosive gives a charge with a density of approximately 1.72 grams per cc. Its brisance, as Judged by the sand test is more than -medium for cyclotrimethylenetrinitr-amine. This can best be shown by a typical example in which a -55 mixture (45% trinitrophenyl methyl nitramine plus trinitrotoluene) is employed as a carrier for the production of a trinitrophenyl methyl nitramine, trinitrotoluene, cyclotrimethylenetrinitramine, ternary explosive composition. In this case, the .maximum quantity of cyclotrimethylenetrinitramine which can be added at the conventional pouring temperatures amounts to 65 parts of cyclotrimethylenetrinitramine to 35 parts of the 45-55 binary mixture. The actual diiferencein explosive power and in rate of detonation between these two compositions is not sufiicient to warrant an exact specification of the compositions to be used or which may be preferred. Consequently, the figures given in the first example and its alternative (Example II) should be considered as approximate and. illustrative but nevertheless producing the desired results.

Example III We have found that it is possible to use a preformed mixture consisting of cyclotrimethylenetrinitramine and 40% trinitrotoluene as a carrier for relatively large quantities of trinitrophenyl methyl nitramine. Thus, for instance, a readily pourable and cast-able ternary composltion of trinitrophenyl methyl nitramine, trinitro toluene and cyc1otrimethylenetrinitramine, can

be prepared by adding parts by weight of trinitrophenyl methyl nitramine to 35 parts by weight of the mixture indicated above at a temperature above to C. Such a composition, when cast, solidifies to a' density of 1.66 grams per cc. and possesses a brisance which is approximately 5% greater than that of the preformed mixture that serves as the carrier. We do not wish to be limited necessarily to the use of the mixture indicated above as a carrier. It has been found, for instance, that it is possible to take a mixture consisting of equal parts by weight of cyclotrimethylenetrinitramine and trinitrotoluene and use this binary composition as carrier for trinitrophenyl methyl nitramine. Such a binary composition can take into suspension an is entirely possible to prepare mixtures of the three ingredients and then .to combine these to produce a pourable ternary composition. We have also found that it is possible to dissolve the three components in acetone and to coprecipitate them either by dilution with water or by adding the acetone solution to a large excess of water. Actual process studies indicate, however, the desirability of using either mixtures of trinitrotoluene plus trinitrophenyl methyl nitramine or mixtures of trinitrotoluene plus cyclotrimethylenetrinitramine both of which are standard explosive compositions, and then subsequente ly adding the respective thir ingredient as, for instance, cyclotrimethylenetrinitramine to the trinitrotoluene plus trinitrophenyl methyl nitramine mixture and trinitrophenyl methyl nitramine to the trinitrotoluene plus cyclotri-' methylenetrinitramine mixture. It should further be mentioned that ternary compositions consisting of trinitrophenyl methyl nitramine, trinitrotoluene and cyclotrimethylenetrinitramine can be made by suitable admixture of preformed mixtures of trinitrotoluene plus trinitr-ophenyl methyl nitramine with mixtures of trinitrotoluene plus cyclotrimethylenetrinitramine.

We also envisage the fact that .certain addends to increase pourability and to inhibit the settling of the solid phase in the molten mixture will not adversely affect ternary mixtures prepared from them. Thus, it has been found that certain surface a-ctive agents such as long chain alkyl, aralkyl and cycloalkyl sulfonated alcohol derivatives, monoand disubstituted amides, ketones, and the like, that is compounds containing a polar atom or group attached to a high molecular weight organic radical will make it possible to produce a trinitrotoluene, cyclotrimethylenetrinitramine mixture containing a higher percentage of cyclotrimethylenetrinitramine than is possible Without their use. Consequently, we do not wish to limit our invention to those castable and pourable ternary compositions described in the examples given above for we believe that addition of surface active agents will make it possible to produce mixtures with still higher percentages of the third ingredient, thereby producing explosives of still higher brisance and power.

It is, of course, well known that many common explosives are much too sensitive to be used as A. P. Shot fillers. In such instances, the addition of a desensitizing wax in percentages varying from 1-10% of the weight of the explosive has been found to make their use feasible for armour piercing shell. The sensitivity to impact of such ternary compositions can be considerably reduced by appropriate additions of a wide variety of waxes such as carnauba, montan, paraflin waxes, etc. The use of an inert nose pad in the shell cavity also makes possible the use of certain more sensitive ternary compositions for armour piercing shell.

Where it is desired to increase the incendiary effect of an explosive filler, the addition of powdered aluminum, of magnesium, of boron, or of alloys of these elements has been found advaning binary mixtures.

brisant explosives.

initiated by mercuric fulminate.

and general terms,

5 action. Addition of these materials has the added advantage in producing greater blast effects.

It should be pointed out that all the properties of the ternary compositions broadly claimed by us indicate their superiority over the correspond- They are non-hygroscopic and, therefore, will not attack or corrode metal components because of inadvertent presence of traces of moisture. The sand test values indicate the superiority of these materials as highly The rates of detonation indicate, furthermore, that such mixtures should have high fragmentation action and, therefore, be particularly useful in such military devices as shells, hand grenades and anti-personnel mines.

20 The ternary explosives, in particular those which can be cast loaded, produce fillers of high density, a factor which is of importance With respect to the power developed on a volume basis by the explosive. All the ternary mixtures are readily Aside from these advantages, such mixtures can be cast loaded by the usual operations which are now employed for loading of other H. E. Fillers.

We have now described our inventions in broad We have indicated certain modifications and extensions which those skilled in the art will be able to recognize as coming within the scope of 'our disclosures. In order to more adequately summarize the general scope as Well as to emphasize preferred compositions and applications, we claim:

The method of preparing a high density explosive composition including trinitrotoluene, trinitrophenyl-methylnitramine and cyclotrimeth- 40 ylenetrinitramine, the said method comprising forming a suspension of cyclotrimethylenetrinitramine in a liquid melt of trinitrotoluene in which trinitrophenyl-methylnitramine is dissolved, and thereafter solidifying the said suspension.

LUDWIG F. AUDRIETH. DE WITT D. SAGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Stettbacker, Nitrocellulose, vol. 11, pages 63-67 (1940) appearing in 1941 Chem. Abs. 4953. 

